Extensible gasket for centrifuge bowls



Fig. 3

INVENTOR.

Sept. 7, 1954 R. M. MELAVEN EXTENSIBLE GASKET FOR CENTRIFUGE BOWLS FiledSept. 11, 1952 Ralph M. Melav BY K fl ATTORNEY Fig; 1

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Patented Sept. 7, 1954 EXTENSIBLE GASKET FOR CENTRI'FUGE BOWLS Ralph M.Melaven, Highland, Ind., assignor to Standard Oil Company, Chicago,111., a corporation of Indiana Application September 11, 1952, SerialNo. 309,053

1 Claim.

This invention relates to centrifugal separating. apparatus and thelike. More particularly, it relates to a centrifugal separator embodyinga novel extensible ring gasket to prevent leakage through annularopenings during high speed operation.

Centrifugal separating equipment is employed in many industries toeffect a physical separation between liquids of different specificgravity. Such equipment ordinarily embodies a bowl which is separable,top from the bottom. And it has been a real problem to properly seal theannular mating surfaces of these two bowl sections,

particularly in those industries handling liquids of high specificgravity. Unlike most sealing problems requiring a gasket, no mechanicalpres sure or other means for clamping the ring in place is available;centrifugal force must be relied upon entirely to maintain the closure.Various gaskets or packings have been employed but none has beencompletely satisfactory. Such gaskets, tobe effective, must beextensible yet sufficiently heavy to remain snug against an annularopening during operation of the apparatus. Since the heaviest liquidmaterial will always migrate to the outside of a rotating centrifuge, itis essential that the sealing ring be heavier than any material beingacted upon.

A primary object of the present'invention is to provide an improved,extensible sealing ring for centrifugal separating equipment. and thelike which will prevent leakage through annular openings during highspeed operation. A further object is to provide a yieldable sealing ringwhich when acted upon by centrifugal force modifies its normal shape toconform to and completely seal off the annular juncture of the upper andlower bowl sections of a centrifugal separating device. An additionalobject is to provide a yieldable and extensible sealing ring which isheavier than the heaviest liquid undergoing separation in a centrifugaldevice. These and additional objects will be apparent from the followingdetailed description of the present invention when considered inconjunction with the attached drawings.

In the drawings, Fig. 1 is a partial elevation view of a conventionalcentrifuge employed in the separation of sludge from acid treatedpetroleum oil with all non-rotary parts removed and with portions of thebowl structure broken away to illustrate the relationship of the novelsealing ring to the equipment as a whole.

Fig. 2 is an enlarged view of that portion of the centrifuge contiguousto the sealing ring shown in Fig. 1.

Fig. 3 is essentially the same View as Fig. 2. but with the sealing ringdistorted, substantially as it would appear under the influence ofcentrifugal force.

Inasmuch as the various elements of the centrifugal equipment to whichthe sealing ring of the present invention is applicable are well-knownto those skilled in the art, only those portions of the equipmentnecessary to completely illustrate the present invention are shown inthe drawing or will be described in detail. A centrifuge of particulardesign is shown in the drawings but the invention is in no way limitedto equipment of such design but is adapted for use in any centrifugalseparating device having sealing problems of the general type described.

In Fig. 1, the bowl of the centrifuge it is surmounted by inlet H andoil outlet l2, concentric thereto. The sludge outlet is aperture ma.Bowl structure lil comprises upper bowl section I3 and.

lower bowl section Hi which are held firmly to gether by annular ringit. Ring 55 is screwed on to section it by means of threads It. Theupper portion of ring l5 forces down on section [3 at E! to cause thetwo bowl sections to be mated annularly at l8. Sealing gasket or ring [9is juxtaposed to annular juncture E3 of the two bowl sections withinannular space 20. Annular space 2.9 is formed by cut-outs in the upperand lower bowl sections and retaining rim or bracket 2| extending upwardfrom the lower bowl section.

Sealing. ring it comprises an extensible doughnut-shaped gasket filledwith a liquid 59a heavier than any liquid being acted upon by thecentrifuge. The various other embodiments of the centrifugal deviceshown, e. g. the separating disks 22, etc. are conventional and shouldnot be considered, per se, a part of the present invention.

Fig. 3 illustrates the manner in whichthe ring is distorted by theinfluence of centrifugal force to conform to the shape of the outerstructure of annular space 20 and to form a complete circumferentialseal so that no liquid may pass through juncture Hi.

It is necessary that the liquid l9a within the yieldable doughnut I9 beof high specific gravity; specifically, it must be higher than theheaviest liquid encountered in a given centrifugal separation. If, forexample, water were contained within the ring during the centrifugalseparation of acid sludge from sour oil, the sludge containing asubstantial amount of sulfuric acid and having an overall specificgravity greater than water would displace the sealing ring from theouter wall of annular space 23 and leakage could occur at juncture 18.In accordance herewith, it is preferred that the ring contain mercury.Other suitable liquids having a high specific gravity, e. g. carbontetrachloride, glycerin, etc. may likewise be employed. Mixtures of suchliquids may also be employed. Whereas the specific gravity of the liquidis preferably substantially greater than 1 it should be understood thatit need only be greater than the heaviest liquid being acted upon in thecentrifuge.

It is preferred, when the sealing ring is to be in contact with acid ofvarying strengths as well as hydrocarbon oils, e. g. in removal of acidsludge from oil, that it be composed of a chemically inert materialwhich is insoluble in most organic solvents. The polyfluoroethyleneplastics, e. g. Teflon, polytetrafluoroethylene resin-a product of E. I.du Font, and Kel-F, polychlorotrifluoroethylene resin-a product of TheM. W. Kellogg Co., are particularly suitable and meet the requirementsof such a gasket. Where the centrifuge is employed to separate liquidswhich do not have a deleterious effect upon the ring, natural orsynthetic rubber or other suitable material, e. g. Neoprene, may beemployed. Polyethylene has been found to be both extensible andresistant to most chemicals and may be employed for the purposedescribed.

Rings of the type employed in accordance herewith are readily preparedby molding or casting in much the same way as for example, automobileinner tubes and the like. The heavy liquid, e. g. mercury, may beintroduced through a suitable aperture which is then sealed. Althoughdescribed with particular reference to a ring shaped gasket, it shouldbe understood that it is within the scope of the invention to employvarious other shapes of mercury-filled yieldable gaskets for sealingopenings which are other than circumferential in nature. Thus, shortlengths of such extensible liquid filled gaskets may be employed. A usefor such a gasket, apart from a centrifuge, is in a device acceleratinglinearly at a high rate, in which it is desired to prevent flow ofliquid during acceleration but to permit same upon attaining a uniformvelocity.

Although the present invention is described with particular reference tothe use of a liquidfilled gasket in conjunction with circumferentialmetal to metal mating surfaces, as shown in the drawings, it should beunderstood that such a sealing ring or gasket is suitable for use inaccordance with any sealing problem encountered in the operation ofcentrifugal equipment or the like. Thus, for example, in certainindustries it is desirable to introduce washing liquid to the centrifugerather than removing the top section of the bowl to clean same. In suchindustries, e. g. the dairy industry, it is common to employ centrifugessimilar to that shown in the drawing but which, rather than having metalto metal contact between the upper and lower sections of the bowl (asindicated by juncture I8), embody a system of annular openings andsupport members or spacers at this location. These annular openings mustbe sealed during the separating cycle, but open during washing. This isachieved by operating at a higher speed during separation than whilewashing. The ring is thus extended to close 01f the annular ports duringseparation but not during the washing cycle. The sealing ring describedherein is very useful in conjunction with such equipment. U. S.2,473,967, U. S. 2,555,542, U. S. 2,482,570, are all directed tocentrifugal equipment employed in the dairy industry and moreparticularly directed to expansible sealing rings for use therein. Thesealing ring of the present invention may be substituted for those shownin the above patents with excellent results.

Having thus described the present invention, what I claim as novel anddesire to protect by Letters Patent, is as follows:

In combination with an apparatus embodying upper and lower bowl sectionsin which centrifugal force may be generated to effect a separation of asulfuric acid sludge from sulfuric acid treated oil, means forpreventing undesired leakage of such liquids through the annularjuncture between said upper and lower bowl sections in such apparatusduring operation thereof which means comprises an extensible hollowsealing gasket comprising a ring of polyfluoroethylene resin filled withmercury, said ring being juxtaposed inwardly of said annular juncture.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 829,546 Schou Aug. 28, 1906 2,139,715 Bergner Dec. 13, 19382,461,655 Noble Feb. 15, 1949 2,597,976 Cousins May 27, 1952 FOREIGNPATENTS Number Country Date 528,359 Great Britain Oct. 28, 1940

